The present invention relates to a microprocessor based, highly integrated generator set controller. More particularly, the present invention relates to an electrical generator set and power system controller capable of sharing real and reactive power with parallel generator sets and further providing for precise frequency, voltage and current regulation while utilizing a single processor. By so doing, system performance, reliability, and cost are optimized.
The output voltage of an electrical generator is determined by the excitation of the field windings of the generator. Therefore, the output voltage of the generator may be controlled in a closed-loop fashion by monitoring its output voltage, comparing that voltage to a reference voltage level, and generating an appropriate signal to the field winding. The speed of the engine driving the generator controls the generator output waveform frequency. Therefore, the freqency of the output waveform may be controlled in a closed-loop fashion by monitoring the revolutions of the engine, comparing the revolutions to a reference and generating an appropriate signal to adjust the engine throttle.
Analog controller systems are widely used in the control of electrical generators. This type of controller typically employs distinct component to independently control the two closed-loop control functions (i.e., the output voltage of the electrical generator and the frequency of the output voltage waveform of the electrical generator). They typiclly do so without sharing information concerning the status of the other closed-loop control function. Further, the circuitry providing for these two control functions are not interconnected to one another. Therefore, in an analog system, not only are the components discrete, but the two control systems are both independent and discete from one another.
Due to their dual discrete design, analog systems also have the disadvantage of requiring duplicate input transformers and circuitry when additional features are added. Also, since the systems are analog, they cannot perform self-diagnostics, indicate their operational state or integrate their control processes to optimize performance. Finally, the discrete controls require calibration for each electrical generator production unit.
There have been attempts to integrate generator set controllers, for example Mezera et al, U.S. Pat. No. 4,322,630, and provide for microprocessor control of the control function. However, none of the attempts have fully integrated the entire generator set control function. Further, none have integrated the precise regulation of fequency, voltage, and current conditions, automatic synchronization of parallel generators, permissive paralleling, and both real and reactive load sharing control during parallel operation. The present invention provides an integrated system and method which provides increased performance over the above described generator set controllers.